http://repository.pauwes-cop.net/handle/1/161 Mon, 27 Apr 2026 14:18:47 GMT 2026-04-27T14:18:47Z http://repository.pauwes-cop.net/handle/1/571 Investigating the major contributing factors to increased flooding in the Nyamwamba catchment using SWAT model-based analysis TIWANGYE, Amans Flooding poses a persistent and critical threat worldwide, impacting lives, infrastructure, and the environment. In the Nyamwamba river catchment, escalating flood events linked to climate change have become increasingly challenging to manage. Despite prior efforts utilizing GIS and hydraulic models, effective flood risk mitigation in the Nyamwamba catchment has proven limited. This research bridges existing gaps by integrating advanced hydrological modeling, specifically the Soil and Water Assessment Tool, with GIS analysis. The main objective is to identify contributors to increased flooding by evaluating SWAT's efficacy in streamflow estimation, analyzing the impact of land use changes and climate variables, and conducting sensitivity analysis. Findings of the Land Use Land Cover change matrix indicated a significant shift in land cover patterns significantly reducing soil infiltration capacity, increasing runoff. Conversion of grasslands to agricultural and built-up areas also led to unsustainable land use practices like cultivation to the river bank, increased paved surfaces, worsening flooding. The monthly time step model showed “Good” calibration with a coefficient of determination R2 of 0.68 and a Nash Sutcliffe Efficiency of 0.63, while Validation demonstrated “Very Good” performance with an R2=0.89. According to future climate scenarios simulated from 2030 to 2080, it’s evident that flow values are significantly influenced by climate variables mainly by precipitation for example under the SSP1-2.6 scenario, where there is an observable trend of increasing precipitation up to 2058 which directly affects the average flow values. Peak flows exceeding the 2013 flood event value of 82m3/s are predicted in 2035, 2047, 2050-2052, and 2054, a period of projected extreme precipitation. The Sensitivity analysis identified Ground Water Delay (GW_DELAY), SCS runoff curve number (CN2), Base Flow Alpha factors (ALPHA_BF), and Soil Available Water Content (SOL_AWC) as highly sensitive, emphasizing their role in causing flood events within the Nyamwamba catchment. Variations in the 4 parameters leads to changes in groundwater recharge rates, runoff generation, base flow contributions, and soil water storage capacity, all of which contribute to the intensification of flooding events. Therefore, this study has provided a holistic determination of causative factors in the Nyamwamba catchment by taking into account the interplay of the various flood contributing factors which will help policymakers and stakeholders to formulate more effective flood management strategies tailored to the unique challenges of the Nyamwamba catchment Mon, 22 Apr 2024 00:00:00 GMT http://repository.pauwes-cop.net/handle/1/571 2024-04-22T00:00:00Z http://repository.pauwes-cop.net/handle/1/570 DROUGHT MONITORING AND ASSESSMENT USING METEOROLOGICAL, HYDROLOGICAL, AND REMOTE SENSING INDICES, CASE STUDY: WADI KHEMIS BASIN (NW ALGERIAN) SOUADJI, Kawter Drought poses significant challenges to water resources, agriculture, ecosystems, and livelihoods in semi-arid regions. Understanding and assessing meteorological, hydrological, and agricultural drought dynamics is crucial for developing effective adaptive strategies and enhancing resilience. This study conducts an integrated assessment of drought patterns in the Wadi Khemis Basin, a semi-arid region in northwest Algeria, from 1982 to 2011, utilizing a combination of meteorological, hydrological, and remote sensing indices. Specifically, the Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), Streamflow Drought Index (SDI), and Normalized Difference Vegetation Index (NDVI) were employed to characterize short- and long-term meteorological, hydrological, and agricultural droughts, respectively. Hydrometeorological stations across the basin with data from 1982 to 2011 were selected for the analysis. DrinC software (Drought Indices Calculator) was used to calculate the SPI, RDI, and SDI values, while Google Earth Engine (GEE) was used to calculate NDVI values. Statistical analyses, including the Mann-Kendall and Sen's slope tests, were conducted to assess trends, and Pearson correlation analysis was performed to investigate the relationships among the three drought types. The analysis identified multi-year meteorological drought episodes in 1983 1984, 1988-1989, and 1998-2000 based on the 12-month SPI and RDI, accompanied by statistically significant upward trends across the short- and long-term timescales. Severe hydrological droughts occurred in 1997-1998, 2005-2007, and 2007-2008 based on the 12 month SDI, with significant downward trends across all timescales. Agricultural droughts were manifested in 1983, 1992, 1998, 1999, and 2002-2008 according to annual NDVI values, with no significant trend detected. Moderate SPI/SDI and RDI/SDI correlations across timescales demonstrate the lagged propagation of meteorological drought impacts through the hydrological system, likely because of the mountainous terrain, spatial variation of the slope, complexity of the hydrographic network, consolidated lithology, permeable soils, semi-arid climate, and karst hydrogeology of the Wadi Khemis Basin. Conversely, poor SPI/NDVI and RDI/NDVI correlations highlight the intricate connection between meteorological and agricultural droughts, influenced by factors such as widespread groundwater exploitation for irrigation, which enhances vegetation resilience to meteorological drought, and the cold winter semi-arid climate, which constrains vegetation growth more than precipitation deficits. This study's findings have significant implications for water resource planning and drought mitigation strategies, contributing to enhanced climate resilience and mitigated drought impacts in the region Wed, 24 Apr 2024 00:00:00 GMT http://repository.pauwes-cop.net/handle/1/570 2024-04-24T00:00:00Z http://repository.pauwes-cop.net/handle/1/565 Assessing the Impact of Climate Change on Hydrological Responses and Sediment Budget in the Ruzizi River Basin AHANA BAYONGWA, Samuel Evaluating the effects of climate change on water resources is crucial for their sustainable management, particularly in hydrologically sensitive regions like the Ruzizi River Basin (RRB) in the Great Lakes area of Africa. This research investigates the impact of climate change on hydrological responses and sediment budget within this critical basin, utilizing the Soil and Water Assessment Tool (SWAT) and advanced climate models. The study is grounded in robust methodologies including the use of Coupled Model Intercomparison Project Phase 6 (CMIP6) datasets under Shared Socioeconomic Pathways (SSP) scenarios SSP2-4.5 and SSP5 8.5. These datasets were downscaled and bias-corrected for fourteen stations using the climate model data for hydrologic modeling (CMhyd) tool, employing the distribution mapping method. The methodology involved comprehensive simulations, sensitivity analysis, and rigorous phases of calibration and validation, achieving a Nash-Sutcliffe Efficiency (NSE) of 0.64 and a Coefficient of Determination (R²) of 0.76 during calibration, with validation results showing an NSE of 0.70 and an R² of 0.74. The research meticulously evaluates historical climatic patterns against future projections, analyzing temperature and rainfall trends through Mann-Kendall tests and exploring the spatial distribution of these variables to ascertain changes across different periods. Results indicated a projected decrease in mean annual precipitation by as much as 35% under both SSP2-4.5 and SSP5-8.5 scenarios by mid and end of the century, leading to significant reductions in water yield by nearly 50% and marginal variations in evapotranspiration. These changes suggest profound impacts on water availability and sediment dynamics within the basin. The study underscores the necessity for proactive and adaptive management strategies in water resource planning and agricultural practices, highlighting the critical need for developing responsive policies and infrastructure investments to enhance resilience against the anticipated disruptions of climate change. This approach will ensure the sustainable management of water resources in the Ruzizi River Basin, preparing for an increasingly uncertain future. Sat, 20 Apr 2024 00:00:00 GMT http://repository.pauwes-cop.net/handle/1/565 2024-04-20T00:00:00Z http://repository.pauwes-cop.net/handle/1/559 ASSESSMENT OF THE IMPACTS OF GROUNDWATER ABSTRACTION ON WATER QUALITY AND QUANTITY IN MAGHRIB B DISTRICT IN ZANZIBAR (UNGUJA) ISLAND VUAI, HIDAYAT AME Zanzibar Island is experiencing a shortage in its water supply, primarily relying on groundwater sources such as shallow wells, boreholes, and cave wells situated on coastal aquifers. The surge in population and the push for tourism growth have intensified the water demand, prompting increased extraction from boreholes. Groundwater abstraction leads to over-exploitation of aquifers and poses risks of pollution, collapse, and seawater intrusion. The main objective of this study was to assess the impacts of groundwater abstraction on groundwater quality and quantity to develop water resources management strategies for sustainable water supply in Zanzibar. This study presents a 40-year rainfall record and temperature analysis to determine how these climatic variables affect groundwater resources in the Island of Zanzibar, Tanzania. In addition, the water table fluctuation, abstraction volume, and different Physio-chemical parameters such as chloride, nitrate, electrical conductivity, and total dissolved solids were also studied. The balance between groundwater recharge and water abstraction rates on the island of Zanzibar was estimated. The water table fluctuation (WTF) method estimated the recharge rate. MODFLOW software was used to analyze and model the aquifer characteristics. Rainfall records showed that Zanzibar Island receives a mean annual rainfall of 1743.1 mm/yr. Temperature variations indicated an incremental trend accompanied by low rainfall. The results also showed that the total groundwater abstraction rate was 1.97×106 m3/yr compared to the recharge rate of about 1.73×106 m3/yr. This means that the groundwater resources are currently over-exploited, and if immediate action is not taken, the groundwater aquifers may be subjected to pollution, collapse, and seawater intrusion. This study compared water quality data from ZAWA against the WHO standards. Most of the water quality parameters were within the WHO limits. However, an increasing trend was observed, especially for parameters related to seawater intrusion. The increasing contaminant trends in Kianga, Bweni, and Chunga may be attributed to long-term groundwater abstraction. The water quality in all boreholes is considered good according to the Water Quality Index classification. Additionally, the study models the aquifer characteristics and found that the water outflow rate is higher than the inflow rate based on the water balance analysis. The results of this study provide crucial insights for water resource managers in Zanzibar, where there is a pressing need for sustainable water resource management due to the imbalance of an outflow and inflow rate Sat, 20 Apr 2024 00:00:00 GMT http://repository.pauwes-cop.net/handle/1/559 2024-04-20T00:00:00Z